DescriptionTelmatobius ventriflavum is a medium sized frog species, with a snout-vent length of 48.5 mm in the single adult male specimen, and 49.3 – 55.7 mm in females. The head is flat, and the snout is rounded with non-widened lips. The region between the nostrils is slightly curved outwards. The region between the eye and the nostril is curved slightly inwards. The nostrils do not protrude, and are directed towards the back of the body. The eyes are large and are closer to the eye than the snout tip. The tympanum and tympanic ring are faint in appearance. The supratympanic fold is prominent, and runs from behind the eye to the level of the shoulder. There is another skin fold running from the supratympanic fold to the post-comissural gland, which is small and oval. The skin on the back is smooth with minute, flat pustules. The underside is smooth. The arms are slim. There is no webbing on the hands, and the fingers lack lateral fringes. The fingertips are spherical. The inner palmar tubercle is evident and ovate, and the outer palmar tubercle is also ovate yet slightly larger. There are five or six rounded supernumerary palmar tubercles. The palms are smooth. Nuptial pads are present on the males. The relative finger lengths are are I = II < IV < III. The legs are long and slim. The upper surfaces of the legs are smooth. The feet are completely webbed, and the toe tips are spherical. The inner metatarsal tubercle is somewhat flattened and ovate, whereas the outer metatarsal tubercle is circular and smaller. The subarticular tubercles are rounded or moderately ovate. There are four small, circular supernumerary tubercles. The soles of the feet are smooth. The relative toe lengths are I < II < III < V < IV (Catenazzi et al. 2015).

It has a distinct bright yellow to orange underside, as well as a distinct golden yellow to brown back with uneven dark brown, golden, and red markings. This species is easy to distinguish from other central Peruvian Andean species of Telmatobius with the exception of T. carrillae and T. intermedius by the absence of premaxillary and maxillary teeth. It can be further distinguished from T. carrillae by the presence of vomerine teeth. It can be distinguished from T. intermedius by its larger size, as T. intermedius reaches only 45 mm in snout-vent length in both sexes whereas T. ventriflavum can reach 55.7 mm in females and 48.5 mm in males. It additionally differs from T. intermedius by its flatter head, absence of minute spines on the skin, and the presence of nuptial spines on the backs and sides of the thumb in males. Another similar species, T. peruvianus, differs from T. ventriflavum by the presence of premaxillary teeth, wrinkled skin on the back, minute spines throughout the body, and large scattered nuptial spines on the thumb. Telmatobius rimac differs in its larger body size (snout-vent length is 70.5 mm in males and 86.9 mm in females), a sturdier built body and limbs, a brown underside, and the underside of the limbs being yellow. Males of T. arequipensis differ by the presence of nuptial spines on the first two fingers. Telmatobius jelskii differs in its larger body size (snout-vent length is 68.6 mm in males and 84.7 mm in females), presence of large tapered nuptial spines on the thumbs, minute spines on chest and throat of males, white to light-grey underside, and yellow orange markings on the legs (Catenazzi et al. 2015).

In life, the back is golden with spots, especially on the head and shoulders, with markings that range from dark brown, to red, or yellow. The sides are light brown-yellow, and the underside is golden to orange-yellow with faint spots on the chest. The undersides of the limb insertions quickly turn from brown-yellow to orange going away from the center of the body and towards the rear. The iris is light grey and has small black speckling. The eyes are bordered by a slender blue-green ring. In ethanol, the backside of the body is greyish brown, with noticeable dark and light grey spots on the back. The underside is light yellow-grey, and the undersides of the limbs are yellowish brown with yellowish grey markings. The undersides of the hands and feet are grey, and the fingers and toes are cream colored (Catenazzi et al. 2015).

Males are smaller than females, though this requires further verification as only one male has been collected for observation. Some individuals have lighter gold/yellow coloring on the back, however most individuals have dark brown, red and yellow spotting on the back. Ventral coloration appears to vary with sex, with males having brighter and more extensive gold and orange coloration on the undersides of their limbs and females having more a subtle coloration similar to the yellow on their throat and abdomen (Catenazzi et al. 2015).

This species is only known from a single locality, a stream tributary of the Huaytará river near Huaytará, Huancavelica Region, Peru. This is in the upper drainage of the Pisco River in the Pacific slopes of the Andes in central Peru. The specimens were collected at 3900 m asl but the type locality extends up to 4300 m asl. The type locality consists of a stream about 10 m wide, with rocky substrate, small waterfalls, and a dam 500 m downstream. The surrounding habitat is sparse and arid. Precipitation in this area is concentrated from January to March, with the remainder of the year being relatively dry (Catenazzi et al. 2015).

Life History, Abundance, Activity, and Special BehaviorsAs the regions surrounding the type locality are arid, it is likely that the dispersal of this species is limited, and they may in fact be endemic to the upper Pisco watersheds and nearby river basins. Numerous tadpoles were found in various stages of development during a collecting event in October 2012, suggesting that the species is able to breed successfully even during the dry season (Catenazzi et al. 2015).

Trends and ThreatsBatrachochytrium dendrobatidis, an infectious fungus that is harmful to amphibians, has been detected in this species. However, more research needs to be done to show the impact of the fungus on T. ventriflavum. It also suffers from a small restricted range that is vulnerable to stream regulation from human infrastructure (dams, reservoirs, pipelines, etc.) as well as contamination from agriculture and mining. (Catenazzi et al. 2015).

Relation to HumansIts single known locality is located near an area of human disturbance, just off the Panamerican highway (Catenazzi et al. 2015).

Possible reasons for amphibian decline

General habitat alteration and lossIntensified agriculture or grazingUrbanizationDisturbance or death from vehicular trafficProlonged droughtMiningDrainage of habitatDams changing river flow and/or covering habitatDiseaseLoss of genetic diversity from small population phenomena

High morphological variation within individual Telmatobius species has made it difficult to determine the phylogenetic relationships within this genus. This new species is morphologically similar to T. intermedius and T. peruvianus, and also resides in a similar habitat, though no genetic analyses have been done to analyze the relationships of these species (Catenazzi et al. 2015).

The specific epithet, ventriflavum, comes from the Latin words venter, meaning belly, and flavus, meaning yellow. This is in reference to the yellow-orange coloration of the underside of the body (Catenazzi et al. 2015).